Tandem-type road roller



' Dec. 10, 1968- B. KALTENEGGER 3,415,174

TANDEM-TYPE ROAD ROLLER Filed Sept. 25. 1966 s Sheets-Sheetl INVENTOR BEN/v0 KAI- TENEG GER 1968 a. KALTENEGGER TANDEM-TYPE ROAD ROLLER 5 Shets$heet 2 Filed Sept. 23, 1966 INVENTOR BEN/V0 KA z. TEA/E6657? Dec. 10, 1968 B. KALTENEGGER' TANDEM-TYPE ROAD ROLLER v Filed Sept. 25. 1966 3 Sheets-Sheet 3 Pi .4 I60 37 340 9 /6b K 29a 29b lab [8b Fig.5 32a 32b 1 19b l9b IN VE N TOR 55mm: K41. TSMEfGfK ATTYJ,

United States Patent O "ice 3,415,174 TANDEM-TYPE ROAD ROLLER Benuo Kaltenegger, Am Pleistalhof, Birlinghoven, Kreis Siegburg, Germany Filed Sept. 23, 1966, Ser. No. 581,540 Claims priority, application Germany, June 11, 1966, K 59,476 15 Claims. (Cl. 9450) ABSTRACT OF THE DISCLOSURE This provides a tandem-type road roller comprising drums lying one behind the other in the direction of travel mounted in a fixed frame. Off center weights are mounted on the shafts of each of the drums. The weights on each of the shafts are mounted so that they are offset by 90 relative to one another on each shaft and to the weights on the shaft of an adjacent drum.

BACKGROUND OF THE INVENTION In some vibrating road rollers of the aforementioned type unbalanced shafts are arranged internally of the roller drums, and an eccentric or off-center weight is associated wtih each shaft. The weights are arranged offset relative to one another from shaft-to-shaft by 180 degrees. Due to this arrangement each unbalanced shaft on rotating through 180 degrees applies a vertical impulse to its associated drum over its entire axial length. It should be noted that since the eccentric weights unbalancing the shafts of the tandem roller are offset by 180 degrees relatime to each other one of the roller drums is loaded by a downwardly directed vibration impulse while at the same time the other roller drum is relieved of any load by the upwardly directed impulse or force of its associated eccentric weight. Accordingly, the impulses travel from one roller to the other and back each time the shafts rotate through 180 degrees.

SUMMARY OF THE INVENTION A primary object of this invention is to provide improvements in vibrating tandenm rollers of the aforementioned type whereby surface compacting is appreciably increased and the time of compacting is materially reduced.

The invention is distinguished from conventional rollers of the aforementioned type in that a plurality of eccentric or off-balanced weights are associated with each shaft, and the eccentric weights of the same shaft and of the shaft mounted in an adjacent drum are each arranged in offset relationship to each other by 90 degrees.

In this way it is possible to obtain vibration forces of extremely great intensity because each time the shafts (generally only two) carrying the weights complete one revolution four impulses are directed toward the surface which is being compacted at successive 90 degree intervals. This arrangement also produces a constantly active and uniform centrifugal force directed toward the ground, as viewed along the axial length of each roller drum. Therefore, a vibrating force is directed toward the ground by each roller drum irrespective of the particular position of the shafts associated with the drums. As a result, the vibrating force directed toward the ground are active at relatively short intervals in both forward and backward travel of the roller thereby resulting in a considerably more intense and rapid compaction of the surface over which the road roller travels and, accordingly, the performance of the road roller is improved considerably.

The eccentric or unbalancing weights can be offset 90 degrees in the manner heretofore described in a variety of different ways beginning, for example, with the impulse 3,4 15,1 74 Patented Dec. 10, 1 968 traveling axially along one shaft in a first axial direction and proceeding along the other shaft in an opposite direction. In this way the vibrations are applied against the ground diagonally of the direction of road roller travel which has been found to be highly advantageous with certain types of ground or soil characteristics. In special cases the off-center weights of the same shaft are offset by 180 degrees and the off-center weights from shaft-toshaft of the road roller are offset by degrees.

In accordance with a further embodiment of the invention a road roller is provided in which each drurn shaft includes four drums provided with two off-center weights each with the off-center weights of the drums adjacent one another being off-set by 90 degrees, and the off-center weights of the drums lying one behind the other offset by degrees. In a tandem road roller of this type the roller, as a whole, is subjected to high-frequency vibrations for surface compaction. Each time the shafts carrying the off-center weights complete one revolution, more than four impulses directed vertically toward the ground are active in succession at 90 degree intervals with the impulses generated by each pair of successive drums acting separately from and unimpeded by the impulses generated by the pair of adjacent drums. Here again the extremely rapid sequence of the vibration forces improve surface compaction very considerably and the performance of the tandem roller is substantially increased by relatively simple but unobvious means.

The tandem road roller of this invention may also be arranged in such manner that the off-center weights within the same drum are offset by 90 degrees relative to one another and the off-center weights of the adjacent drums are offset by 45 degrees relative to each other, in which the case the off-center weights of the drums lying one behind the other are offset by 180 degrees relative to one another. By virtue of this arrangement the extent of the vibration, as viewed along the axis of the drums lying one behind the other, remains in excess of half a complete deflection. When the off-center weights are distributed or arranged in the manner just described, the drums lying one behind the other can each be mounted in a frame with the frames being pivotally mounted about a common central axis. The adjacent shafts can be, for example, interconnected by elastic couplings, or each pair of successive drums is mounted in a r-igid frame connected with an adjacent frame by elastic buffer members, while the unbalanced shafts of adjacent drums are connected to each other by elastic couplings.

BRIEF DESCRIPTION OF DRAWINGS Specific embodiments of the invention will be described immediately hereinafter with reference to the accompanying drawings in which:

FIG. 1 is a highly diagrammatic perspective view of a tandem road roller constructed in accordance with this inveniton, and illustrates a pair of roller drums and eccentric weights associated with the shafts thereof;

FIG. 2 is a highly diagrammatic partial sectional view of another tandem road roller of this invention, and illustrates two pairs of adjacent roller drums and a pair of eccentric weights associated with each of the shafts thereof;

FIG. 3 is a sectional view taken generally along line IlI-III of FIG. 2, and illustrates the rotational offset relationship of eccentric weights carried by upper and lower drums of the tandem roller;

FIG. 4 is a highly diagrammatic partial sectional view of another tandem road roller of the invention, and illustrates elastic couplings between adjacent drums mounted in a rigid frame of the roller, and a pair of eccentric weights carried by the shaft associated with each drum; and

3 FIG. is a diagrammatic view of the shafts of the roller of FIG. 4, and illustrates relative positions of the eccentric weights carried thereby during the rotation of the shafts.

DESCRIPTION OF SPECIFIC EMBODIMENTS A novel road roller of the tandem-type constructed in accordance with a first embodiment of the invention is shown in FIG. 1 and includes a pair of rolls or drums 2, 3 mounted one behind the other in a single, rigid frame consisting of a pair of side frames 4, 4 and end frames 5, 5. The axes of the drums 2, 3 are in parallel relationship and are disposed generally normal to the forward direction of roller travel which is indicated by the directional arrow 9, the reverse or backward direction being, of course, opposite thereto. Unbalanced shafts 6, 7 are associated with the respective drums 2, 3, and the shafts 6, 7 are suitably journaled in the side frames 4, 4. The shafts 6, 7 and the drums 2, 3 respectively associated therewith are normally rotated counterclockwise to drive the road roller 1 in the direction of the arrow 9, or in an opposite direction, by a belt or chain 8 entrained about pulleys (unnumbered) fixed to the shafts, at least one of which is driven by an engine or similar conventional means (not shown) in both clockwise and counterclockwise directions, as desired.

Each of the shafts 6, 7 is provided at its axially opposite ends with eccentric weights 10, 11 and 12, 13, respectively. The weights through 13 are each offset circumferentially by 90 degrees relative to each other, including the weights on one and the same shafts 6, 7 whereby the weights are thereby offset diagonally relative to each other. With this arrangement four downwardly directed impulses or forces are generated during each 360 degree revolution of the shafts 6, 7, and are further directed diagonally, as well as longitudinally, of the roller drums 2, 3.

The road roller of FIG. 1 is but one embodiment of the invention which achieves the advantages heretofore noted, but in accordance with another embodiment of the invention the road roller (FIGS. 2 and 3) may inelude pairs of adjacent drums 16a, 16b and 17a, 17b arranged one behind the other normal to the forward and backward directions of travel of the roller. The

drums 16a, 16b, 17a and 17b are mounted on shafts 18a, 18b, 19a and 19b, respectively which is journaled for rotation in frames 20, 21 of the roller. The shafts 18a, 18b, 19a and 19b carry respective eccentrically mounted weights 29, 29; 30, 30; 31, 31 and 32, 32, and the rigid frames are mounted for pivoting movement relative to each other about a common shaft 22 with a collar 22a maintaining the frames 20, 21 in spaced relationship to each other. The shafts 18a and 19a are connected to the respective shafts 18b, 19b by elastic couplings 35, 36, respectively. The couplings 35, 36 may be, for example, socket-type connections coupled together by elastic members such as, for example, blocks of rubber, plastic or similar elastic materials. The shafts 18a, 18b, 19a and 19b are rotated commonly in either of clockwise or counterclockwise directions by means of a belt or chain 25 entrained about pulleys 26, 27. Suitable means (not shown), such as an engine or motor, is connected to drive the shafts through the pulley 28.

The off-center or eccentric pairs of weights 29, are offset by 90 degrees relative to the offset weights 31, 32 of adjacent drums, while the weights 29, 30 and 31, 32 are arranged 180 degrees offset to each other in the drums lying one behind the other. In the embodiment of the invention shown in FIG. 2 the weights 31 are located beneath the shaft 19a while the weights 29 are located above the shaft 18a. In this arrangement the offcenter or eccentric weights 30, 32 are each located on the outside of their associated shafts. Thus, each time the drums complete a quarter turn or revolution the weights 4 of one drum are in a lowermost position thereof and the pairs of drums lying one behind the other can swing or pivot a limited amount about the central shaft 22.

In the embodiment of the invention illustrated in FIG. 4 of the drawings drums 16a, 17a and 16b, 17a and 16b, 17b lie one behind the other and are journaled for rotation in respective generally rectangular rigid frames 33, 34 by respective unbalanced shafts 18a, 18b and 19a, 19b. The shafts 18a, 18b and 19a, 19b are coupled together by flexible elastic couplings 35, 36, respectively. Adjacent innermost frame members 33a and 34a of the respective frames 33, 34 are resiliently interconnected by elastic buffer blocks 37, 38. Each of the drums 16a 16b, 17a and 17b is provided with two off-center or eccentric weights 29a, 29b; 30a, 30b; 31a, 31b and 32a, 32b, respectively. The relative positions of the eccentrically mounted weights is clearly illustrated in FIG. 5 of the drawings in which it will be noted that the position of the eccentric weights relative to one another is such that the weights within any one drum are offset circumferentially by degrees relative to each other and the eccentric weights of the adjacent drum are offset circumferentially by 45 degrees relative to each other while the weights of the drums lying one behind the other are offset by degrees. Thus, in this arrangement of the weights 29a, 29b and 30a, 3011 on the shafts 18a and 18b of adjacent drums, and of the weights 31a and 31b of the drum 17a and the weights 32a and 32b of drum 17b, an impulse or force directed toward the ground is generated each time the drums of the tandem road roller as a whole complete one-eighth of a revolution resulting in excellent surface compaction.

What is claimed as new is:

1. A tandem road roller for producing a vibration impulse comprising:

(a) a rigid frame,

(b) a pair of shafts mounted one behind the other on said frame,

(0) a drum means mounted on each shaft,

(d) means for moving the roller in a direction substantially normal to the shaft axis,

(e) a pair of eccentric weights mounted in circumferentially offset relationship to each other on each shaft, and

(f) the weights in a corresponding position on each of said shafts being circumferentially offset relative to each other.

2. A tandem road roller as defined in claim 1 wherein the said pair of eccentric weights mounted on each shaft are circumferentially offset relative to each other by 90 and the Weights in a corresponding position on each of said shafts are circumferentially offset relative to each other by 180.

3. A tandem road roller as defined in claim 1 wherein the said pair of eccentric weights mounted on each shaft are circumferentially offset relative to each other by 180 and the weights in a corresponding position on each of said shafts are circumferentially offset relative to each other by 90.

4. A tandem road roller for producing a vibration impulse comprising:

(a) a rigid frame structure,

(b) a shaft means mounted one behind the other in said frame structure,

(c) a pair of drums mounted on each shaft means,

(d) means for moving the roller in a direction substantially normal to the shaft means axis, and

(e) a pair of eccentric weights mounted on the shaft means with respect to each drum, the weights in a corresponding position on the shaft means with respect to each drum being circumferentially offset from each other.

5. The tandem road roller as defined in claim 4 wherein said rigid frame structure consists of a pair of adjacent rigid fraimes,

said shaft means consists of a separate shaft for each drum,

the shafts of adjacent drums are in coaxial relationship to each other and are disposed normal to the direction of roller travel, and

means coupling adjacent shafts to each other provide relative movement therebetween.

6. The tandem road roller as defined in claim 5 Wherein means are provided for pivotally connecting said frames to each other for pivoting movement about an axis normal to the direction of roller travel.

7. The tandem road roller as defined in claim 4 wherein said rigid frame structure consists of a pair of adjacent means are provided for pivotally connecting said frames to each other for pivoting movement about an axis normal to the direction of roller travel.

8. A tandem [031d roller as defined in claim 4 wherein the weights of each said pair of eccentric weights are circumferentially aligned relative to each other.

9. The tandem road roller as defined in claim 8 wherein the Weights of adjacent drums are offset by 90 degrees relative to one another, and the weights of successive drums in the direction of roller travel are offset relative to one another by 180 degrees.

10. A tandem road roller as defined in claim 4 wherein the weights of each said pair of eccentric weights are circumferentially offset relative to each other.

11. The tandem road roller as defined in claim 10 wherein the Weights associated with the same drum are offset circumferentially by 90 degrees relative to each other.

12. The tandem road roller as defined in claim 10 wherein the weights associated with the same drum are offset circumferentially by 90 degrees relative to each other, and the weights of the drum adjacent said latter mentioned drum are offset circumferentially by degrees relative to each other whereby the weights of the drums lying one behind the other are offset circumferentially by degrees relative to each other.

1.3. The tandem road roller as defined in claim 12 wherein said rigid frame structure consists of a pair of adjacent rigid frames, and

means are provided for pivotally connecting said frames to each other for pivoting movement about an axis normal to the direction of roller travel.

14. The tandem road roller as defined in claim 13 wherein there is a shaft associated with each drum, the shafts of adjacent drums are in coaxial relationship to each other and are disposed normal to the direction of roller travel, and means are provided for coupling the adjacent shaft to each other while providing relative movement therebetween.

15. The tandem road roller as defined in claim 13 wherein elastic buffer means are provided between the pair of frames in interconnected relationship thereto.

References Cited UNITED STATES PATENTS 2,633,781 4/1953 Day 9448 2,743,585 5/1956 Berthet 9448 X 3,038,350 6/1962 Meyer 94--50 X 3,048,089 8/ 1962 Kaltenegger 9450 3,053,157 9/1962 Martin 9450 3,082,668 3/1963 Matson 9450 3,097,537 7/1963 Peterson 94--48 X 3,309,972 3/1967 Peters 9450 NILE C. BYERS, IR., Primary Examiner. 

